Originally Posted by Gerry R
It seems that as oil leaks past the plate it is probably blown back hitting the wires which are quite close by. A really crappy place as it almost assures getting oil on them. And I might add that the amount of oil leakage is very small, I usually go 6-7k miles between changes and it has never been low enough to need to add.
Oil on the wires will not damage the sensors, it will interupt the signals but once cleaned off all should work as normal, I think these sensors were only changed to make money for some workshop or they did not know what they were doing.